1. Field of the Invention
The present invention relates to a light emitting semiconductor device that uses a Group III nitride compound. Specifically, the invention relates to a LED and to flat or panel-type display utilizing light-emitting semiconductor elements that are formed on a substrate and selectively enabled to emit light of a single color or one of the three primary colors at s time.
2. Description of the Related Art
It has been known that an aluminum gallium indium nitride (AlGaInN) compound semiconductor may be used to obtain a light-emitting diode (LED) which emits blue light). This semiconductor device is useful because of its high luminous efficiency resulting from direct electron transition and because of its ability to emit blue light, which is one of the three primary colors.
Irradiating an electron beam into and heat treatment of a magnesium (Mg) doped i-layer alters the layer to exhibit p-type conduction. As a result, s LED with a double hetero p-n junction structure made of an aluminum gallium nitride (AlGaN) p-layer, a zinc (Zn) doped indium gallium nitride (InGaN) emission layer, and an AlGaN n-layer becomes useful instead of a conventional LED of metal insulator semiconductor (MIS) structure that includes an n-layer and a semi-insulating i-layer.
The emission layer of the LED with a double hetero p-n junction structure is doped with only Zn as the luminous center and exhibits semi-insulative characteristics. Electrons are injected from the n-layer and holes from the p-layer into the emission layer. Light is emitted by the recombination of those injected electrons and holes when the diode is forward biased.
Several experiments were carried out altering the doping amount of the donor and the acceptor impurities into the emission layer and measuring the luminous colors emitted. As a result, the luminous colors were found by the inventors of the present invention to change depending on the amount of donor and acceptor impurities.